JP4068849B2 - Automotive suspension parts having offset parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile suspension component having an offset portion formed by bending an arm portion.
[0002]
[Prior art]
In recent years, aluminum forged parts that are lightweight and highly reliable are often used for automobile suspension parts. This is because suspension parts are important safety parts for automobiles and weight reduction is desired from the viewpoint of improving fuel consumption.
FIG. 3 shows a conventional example of such an automobile suspension part. As shown in FIG. 3A, the automobile suspension component 101 is pivotally connected to a mounting portion 102 for pivotally connecting to a knuckle arm (not shown) connected to the wheel of the automobile and a bracket (not shown) on the vehicle body side. For example, and an attachment portion 104 and an attachment portion 104, which are connected by an arm 105. Further, the arm portion 105 has a concave portion 106 at the center portion and an offset portion 107 that is curved with respect to the plane D in the middle from the attachment portion 102 to the attachment portion 104 as shown in FIG. ing. The plane D is a plane connecting the attachment portion 103, the attachment portion 104, and the attachment portion 102, or a straight line.
[0003]
Such an automobile suspension part 101 includes an arm part 105 offset in order to avoid interference with other parts. This will be described by taking, as an example, the stress distribution in the CC cross section, which is a cross section obtained by cutting the offset portion 107 along a plane perpendicular to the plane D. FIG. 4 is a schematic diagram showing the shape of the CC cross section of FIG. 3A and the stress distribution thereof.
[0004]
The concave portion 106 of the arm portion 105 is formed for the purpose of light weight design. In this example, as a cross-sectional shape, as shown in FIG. 4, the upper end surface 108 serving as the outer end surface is closed, and also becomes the outer end surface. The lower end surface 109 has an open substantially U shape. When a load is applied to the attachment portions 102, 103, and 104 (see FIG. 3), a stress σ _x (see FIG. 4) due to the x component of the load is generated. The stress σ _x increases linearly toward the outer end surface with the stress neutral point 110 of the cross section as the center.
[0005]
Next, a method for manufacturing such an automobile suspension component 101 will be described. The automotive suspension component 101 is lightweight and requires high strength and fatigue strength, but also requires high impact resistance. For this reason, by forging 6000 series aluminum alloys such as A6061 and its improved materials Molded. The mold used for the forging process is manufactured such that the upper and lower mold parting lines are positioned on the upper end surface 108 of the automobile suspension part 101 or on the side surface near the lower end surface 109 on the opposite side. .
[0006]
This is due to consideration of forgeability and facilitation of mold manufacture. Further, the parting line part is a part where surplus aluminum alloy is discharged as burrs during forging, and the burrs are removed by trimming. Therefore, the automobile suspension part 101 formed in this way has a party which is a burr surface formed of a shear surface after removing the burr at a position corresponding to the parting line, that is, a side surface in the vicinity of the upper end surface 108. A ring line 112 is formed. In addition, the conventional parting line 112 may be formed in the side surface of the vicinity of the lower end surface 109 for the same reason.
[0007]
[Problems to be solved by the invention]
However, since such a parting line 112 has an uneven shape caused by shearing, stress is concentrated and tends to be a starting point of fatigue failure, and the fatigue strength is about 15% lower than other parts. I know.
[0008]
That is, the fatigue strength against bending in the vertical direction in the vicinity of the upper end surface 108 is lowered by 15% due to the parting line 112, and the actual allowable stress in this portion is reduced by 15%. As shown in FIG. 4, when the actual allowable stress is reduced by 15% in the region where the stress σ _x is large, the strength is insufficient. Therefore, the design stress in the vicinity of the upper end face 108 having the parting line 112 is 15% higher than that of the other portions. It was necessary to calculate the strength and estimate the wall thickness etc.
[0009]
Thus, when designing according to a portion having a low allowable stress, the cross-sectional area of the offset portion 107 is increased, and the weight of the automobile suspension component is also increased. Furthermore, when the cross-sectional area is increased, the general portion, which is a portion other than the formation position of the parting line 112, has a strength that is 15% higher than the originally required fatigue strength. There was no excess quality.
[0010]
Accordingly, the present invention was devised in view of the above-described problems, and an automotive suspension component having an offset portion that can ensure the fatigue strength of the automotive suspension component while suppressing an increase in weight. The purpose is to provide.
[0011]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention that solves the above-described problems includes a plurality of attachment portions for connecting the wheel and the vehicle body, an arm portion provided with the attachment portion at an end portion, and the arm portion and the attachment portion. And a parting line that is a removal surface for burrs generated during forging, and has a recess having a U-shaped cross section in the arm part, and a reference surface that connects the attachment part to the arm part in a straight line. in automotive suspension component having an offset portion that is curved Te, the arm portion includes a first surface located on a reference surface in the offset portion, and a second surface opposite to the first surface, the first surface Offset portion having a parting line on a side surface less than 0.85 times the distance from the stress neutral point to the first surface or the second surface in the cross section of the offset portion Have And the automotive suspension parts.
[0012]
The suspension part for an automobile having the offset portion configured as described above is provided with a parting line on the center side by a predetermined distance from the first surface and the second surface where the maximum stress is generated, thereby reducing the strength due to the parting line. Even if this occurs, the overall fatigue strength of the offset portion is prevented from being lowered. Since such a parting line is located in a region where the actual stress generated is lower than the allowable stress at the time of design, even if the fatigue strength of the parting line is lower than other parts, the side surface In this case, the strength of the parting line is not the lowest, and breakage from the parting line can be prevented. In particular, by providing a parting line at a position less than 0.85 times the distance from the stress neutral point to the first surface or the second surface in the cross section of the offset part, fatigue failure from the parting line is ensured. Can be prevented.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1A is a plan view of a suspension part for an automobile, and FIG. 1B is a side view. FIG. 2 is a cross-sectional view taken along line AA in FIG.
[0014]
As shown in FIGS. 1 (a) and 1 (b), an automotive suspension component 1 (hereinafter simply referred to as a suspension component 1) includes an attachment portion 2 for connection to the wheel side and an attachment for connection to the vehicle body side. As shown in FIG. 1 (b), the arm portion 5 has an arm portion 5 having end portions 3 and 4 at an end portion, from a plane B serving as a reference plane passing through the attachment portions 2, 3, and 4. Also has an offset portion 7 in which the arm portion 5 is curved on the lower side. Such a suspension component 1 is used as an upper arm or a lower arm of an automobile suspension.
[0015]
In this example, the arm portion 5 is formed with a recess 6 in the central portion, and the cross section perpendicular to the plane B is close to the plane B as shown in FIG. An upper end surface 8 that is a first surface of the arm portion 5 to be performed, a lower end surface 9 that is a second surface at a position facing the upper end surface 8, and a side surface 11 that extends from the upper end surface 8 to the lower end surface 9. The upper end surface 8 is closed, and the lower end surface 9 is open. Further, the side surface 11 of the arm portion 5 has a parting line 12 which is a burr surface formed when the burr formed at the time of forging is removed. In FIG. 2, the side surface 11 includes an inclined surface 11 </ b> A that decreases in cross-sectional width from the parting line 12 to the upper end surface 8, and an inclined surface 11 </ b> B that decreases in cross-sectional width from the parting line 12 to the lower end surface 9. And have. These inclined surfaces 11A and 11B are inclined corresponding to the draft angle of the mold in the forging process of the suspension component 1 described later.
[0016]
Here, when such a suspension component 1 is attached to an automobile, a load acts on the attachment portions 2, 3, 4, and stress is generated in the offset portion 7. Among such stresses, the stress σ _x that generates a moment about the x-axis shown in FIG. 2 is such that the upper end surface 8 and the lower end surface 9 have the maximum value σ _F and gradually decrease toward the stress neutral point 10 of the cross section. Has a linear distribution. Note that the stress applied above the stress neutral point 10 and the stress applied below the stress neutral point 10 are acting in the opposite direction. Further, the position of the stress neutral point 10 is determined by the cross-sectional shape of the offset portion 7, and does not necessarily come to the position of FIG.
[0017]
Such an offset portion 7 performs strength calculation using the maximum stress σ _F generated on the upper end surface 8 and the lower end surface 9 as an allowable stress, determines its cross-sectional area, and compares it with the inclined surfaces 11A and 11B, which are general portions. Thus, the parting line 12 having a fatigue strength of 15% is formed at a position where a predetermined amount of stress is generated less than the allowable stress (maximum stress σ _F ). An example of such a position is a position below the position P1 that is 0.85 times the maximum stress σ _F in the stress distribution of FIG. This is to prevent insufficient strength at the formation position of the parting line 12 by forming the parting line 12 in a region where only a stress 15% or more smaller than the maximum stress σ _F is generated.
[0018]
Here, when the formation position of the parting line 12 is defined as the distance L _p from the plane E passing through the stress neutral point 10 and parallel to the plane B to the formation position of the parting line 12, the distance L _p can be set. Do range L _C is 0.85 times the stress of maximum stress sigma _F is the position P1 acting on the upper end face 8 side, a position where 0.85 times the stress of maximum stress sigma _F acts at the lower end face 9 side If it is between P2, it will be good. When this is expressed by a distance e ₂ from the plane E to the upper end surface 8 and a distance e ₁ from the plane E to the lower end surface 9, the distance L _p is zero or more when the distance e ₁ is the distance e ₂ or more. Is less than 0.85 times the distance e ₁ . When the distance e ₁ is less than the distance e ₂ , L _p is zero or more and less than 0.85 times the distance e ₂ . That is, the larger the distance e ₁ or the distance e ₂ , the larger the distance L _P , and the parting line 12 may be provided at a position less than 0.85 times the maximum stress σ _F. If it is less than the range of the distance L _p vertically around a stress neutral point 10 of the set position of the parting line 12, without reducing the design stress of 15%, it is possible to secure the strength of the cross-section.
[0019]
As described above, in the suspension component 1 of the present embodiment, even if the fatigue strength of the parting line 12 is reduced by 15% compared to the general part by forming the parting line 12 in the above-described setting range L _C. It can be prevented from breaking from here. That is, since sufficient strength can be ensured only with the allowable stress of the general part, it is possible to reduce the section modulus as compared with the case where the strength calculation is performed in consideration of the strength decrease due to the parting line 12. Become. Thereby, a cross-sectional shape can be reduced in size and the suspension component 1 as a whole can be reduced in weight by 8 to 15%.
[0020]
The manufacturing process of the suspension component 1 will be briefly described.
First, the manufactured aluminum alloy material is cut into a predetermined shape, heated to a predetermined temperature, and then hot forged. Then, when the burrs formed by forging are trimmed, the suspension component 1 shown in FIG. 1A is completed. Mold used in the forging process is divided as a boundary between the upper and lower molds parting line is located at the parting line Setting Range L _C shown in FIG. That is, in the suspension component 1, a portion on the upper end surface 8 side from the parting line 12 is formed by the upper die, and a portion on the lower end surface 9 side from the parting line 12 is formed by the lower die.
[0021]
The present invention is not limited to the above embodiment and can be widely applied. For example, the suspension component 1 can be manufactured from other alloys or steel materials. Further, the shape of the suspension component 1 can be changed as appropriate, such as having a through hole instead of the arm portion 5 having the recess 6.
Further, in FIG. 1B, the parting line 12 is located within the set range L _C over the entire circumference of the suspension component 1, but only the offset portion 5 is within the set range L _C. If it is within the range, it is possible to achieve the operations and effects of the embodiment.
[0022]
【The invention's effect】
According to the present invention, since it is possible to obtain a suspension part for an automobile with a cross-sectional shape by fatigue strength calculation when there is no parting line, it is possible to reduce the shape while maintaining sufficient fatigue strength, Weight reduction can be achieved.
[Brief description of the drawings]
1A is a plan view and FIG. 1B is a side view of an automotive suspension component according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3A is a plan view of a conventional automobile suspension component, and FIG. 3B is a side view thereof.
4 is a cross-sectional view taken along the line CC of FIG. 3 (a).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Automobile suspension components 2, 3, and 4 Mounting part 5 Arm part 7 Offset part 8 Upper end surface (1st surface)
9 Lower end surface (second surface)
10 Stress neutral point 12 Parting line (Burr surface)
B plane L _C setting range

Claims (1)

A plurality of attachment parts for connecting the wheel and the vehicle body, an arm part provided with the attachment part at an end, and a parting line which is a removal surface of burrs generated during forging across the arm part and the attachment part A suspension part for an automobile having a recess having a U-shaped cross section in the arm part, and having an offset part curved with respect to a reference surface connecting the attachment part in a straight line to the arm part,
The arm portion includes a first surface located on the reference surface side in the offset portion, a second surface facing the first surface, and a side surface extending from the first surface to the second surface. And the parting line is provided on the side surface that is less than 0.85 times the distance from the stress neutral point in the cross section of the offset portion to the first surface or the second surface. An automotive suspension component having an offset portion.

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